Table 1.

Types of phage display libraries and their defining characteristics

	Type of library
Characteristic	Naive	Immune	Synthetic/semisynthetic
Repertoire	Large, from healthy human donors	Small, from immunized source	Artificial or combination of artificial and naturally introduced diversity in CDRs
Diversity (no. of unique mAb clones)	10⁹–10¹¹, depending on number of donors	10⁶–10⁸	Usually equivalent to fully naive
Affinity	Can be low and require maturation	Usually higher due to prior in vivo affinity maturation	Can be low and require maturation
Humanization	Not required	Required	Not required
Application	Target-agnostic	Target-specific	Target-agnostic
Developability	May encounter developability issues due to inherent sequence liabilities	Humanization may be required	Framework selection may be limiting